In present day automotive air conditioning systems, a refrigerant compressor is driven by the vehicle engine; the hot compressed refrigerant gas, typically Freon, from the compressor is supplied to a condenser for cooling and liquifying the refrigerant gas. The outlet of the condenser is connected to a receiver/dehydrator which holds a reserve quantity of the refrigerant and separates the gaseous refrigerant from the liquified refrigerant. A desiccant in the receiver/dehydrator removes moisture from the refrigerant. The liquid refrigerant is supplied from the outlet of the receiver/dehydrator to an expansion valve which controls the flow of refrigerant to an evaporator. In the evaporator, the liquid refrigerant passes through a heat exchanger and is vaporized by the absorption of heat from circulating air from the passenger compartment for cooling by the air conditioning system. The vaporous refrigerant from the outlet of the evaporator is returned to the suction side of the compressor.
In the prior art, the receiver/dehydrator and the expansion valve has been constructed as separate units as shown, for example, in the Widdowson U.S. Pat. No. 3,953,984 granted May 4, 1976. In the air conditioning system shown in that patent, the expansion valve is disposed within the same housing as a freeze sensor-actuator and a refrigerant bypass valve assembly for maintaining the evaporator temperature above a freezing level. The expansion valve is controlled by a bellows which is responsive to the pressure of the refrigerant at the inlet of the evaporator. A pressure decreases operates to unseat a ball valve and increase refrigerant flow through the expansion valve. The expansion valve is provided with a bleed passage in bypass relationship to the valve to provide a minimal flow of refrigerant to the evaporator.
An automotive air conditioning system in which the receiver/dehydrator and the expansion valve are contained in the same housing is disclosed in the Widdowson U.S. Pat. No. 3,965,693 granted June 29, 1976. In this system, the same housing also encloses a suction throttling valve which is utilized to control the suction line pressure and prevent frost formation on the evaporator. The container or housing for the receiver/dehydrator is provided with an inverted cup-shaped cover which is provided with an inlet fitting connected to the suction line extending from the outlet of the evaporator. The expansion valve is thermostatically operated and utilizes an actuator of the adsorbent type which is responsive to the temperature of the refrigerant at the suction side of the evaporator. The cover on the receiver/dehydrator is bolted in position and could be oriented in different positions to accommodate the connection of the suction line from the evaporator.
In automotive air conditioning systems, it is known in the prior art to utilize an expansion valve which is actuated in response to either pressure or temperature of the refrigerant in the evaporator suction line. The known actuators take one of several different forms. In the Widdowson U.S. Pat. No. 3,953,984 discussed above, a pressure responsive bellows is used as an actuator. In the Widdowson U.S. Pat. No. 3,965,693 discussed above, the expansion valve is operated by a temperature responsive actuator contained within the housing of the valve and the receiver/dehydrator. In the Widdowson U.S. Pat. No. 3,962,884 granted June 15, 1976, an expansion valve is illustrated which is actuated by a thermal bulb on the evaporator suction line which is coupled with the valve through a capillary. It is also known in automotive air conditioning systems to utilize a solenoid actuated expansion valve controlled by an electronic circuit in response to an electrical signal from either a temperature or pressure sensor in the evaporator suction line.
A general object of this invention is to provide an improved integrated receiver/dehydrator and expansion valve which overcomes certain disadvantages of the prior art.